Drive device and method for driving a drill rod

ABSTRACT

The invention relates to a drive device for driving a drill rod, which has an outer rod and an inner rod, with a first rotary drive unit, with which the outer rod can be driven in a rotating manner via an outer drive shaft, a second rotary drive unit, with which the inner rod can be driven in a rotating manner independently of the outer rod via an inner drive shaft, and a vibration unit for generating a vibration, which has a vibration element that can be driven in a vibrating manner. For transmission of the vibration to the outer drive shaft the vibration element is connected via a first transmission unit to the outer drive shaft and for transmission of the vibration to the inner drive shaft the vibration element is connected via a second transmission unit to the inner drive shaft.

The invention relates to a drive device for driving a drill rod, whichhas an outer rod and an inner rod, in accordance with the preamble ofclaim 1. Furthermore, the invention relates to a method for driving adrill rod in accordance with the preamble of claim 12.

The drive device comprises a first rotary drive unit, with which theouter rod can be driven in a rotating manner via an outer drive shaft, asecond rotary drive unit, with which the inner rod can be driven in arotating manner independently of the outer rod via an inner drive shaft,and a vibration unit for generating a vibration, which has a vibrationelement that can be driven in a vibrating manner.

In the method provision is made in that by means of a first rotary driveunit the outer rod is driven in a rotating manner via an outer driveshaft, in that by means of a second rotary drive unit the inner rod isdriven in a rotating manner independently of the outer rod via an innerdrive shaft and in that by means of a vibration unit a vibration isgenerated.

The drive device is especially provided for the so-called double-headdrilling, in which an outer rod and an inner rod received therein aredriven by two independent rotary drive units.

To drive the outer rod the drive device comprises an outer drive shaftwhich can be coupled with the outer rod. To drive the inner rod thedrive device comprises an inner drive shaft which can be coupled withthe inner rod.

The outer rod can, in particular, be a drill pipe which stabilizes theground surrounding the drill-hole as a casing. The inner rod runs insidethe outer casing and can have ground working tools for removing groundmaterial and/or a conveyor flight for conveying ground material.

To improve the drilling progress it is known that in addition to therotary drives a vibration drive is provided with which a vibration oroscillation can be transmitted to the outer rod or the inner rod.

In DE 20 2010 014 478 U1 a drive device for a drill rod is describedwhich has a vibration unit for transmitting an oscillation to the drillrod.

The invention is based on the object to provide a drive device and amethod for driving a drill rod which allow for a particularly efficientproduction of a drill-hole.

In accordance with the invention the object is solved by a drive devicehaving the features of claim 1 and by a method having the features ofclaim 12.

In the case of the drive device provision is made in accordance with theinvention in that for transmission of the vibration to the outer driveshaft the vibration element is connected via a first transmission unitto the outer drive shaft and for transmission of the vibration to theinner drive shaft the vibration element is connected via a secondtransmission unit to the inner drive shaft.

The method according to the invention is characterized in that thevibration generated by the vibration unit is transmitted via a firsttransmission unit to the outer drive shaft and via a second transmissionunit to the inner drive shaft.

A fundamental idea of the invention resides in the fact that in the caseof a drive device having independent rotary drill drives for the outerrod and the inner rod a common vibration unit is provided whichgenerates a vibration or oscillation that is transmitted to both theouter rod and the inner rod. Hence, according to the invention one andthe same vibration or oscillation is transmitted to the outer rod on theone hand and to the inner rod on the other hand.

As a result of the invention the need for a second vibration unit isdisposed of. Thus, the drive device becomes compact whilst requiring alow amount of power. Moreover, compared to percussive drilling,vibration drilling is quieter and lateral friction is overcome moreeasily.

The vibration unit comprises a vibration element or a vibration bodywhich is moved up and down in the longitudinal direction of the drillrod, i.e. it oscillates or vibrates. By means of transmission units,which transmit the oscillation or vibration of the vibration element,the vibration body is operatively connected to both rods or both driveshafts.

The drive shafts of the drive device can preferably be driven atdifferent speeds and/or in different directions. The first rotary driveunit exclusively drives the outer rod and the second rotary drive unitexclusively drives the inner rod.

By preference, the vibration unit comprises a non-rotating vibrationelement, the axial oscillation of which is transmitted via thetransmission units to the rotating drive shafts. To transmit theoscillation of the vibration element to the outer rod and the inner rodit is preferred in accordance with the invention that the firsttransmission unit has at least a first pivot bearing, via which theouter drive shaft is supported in a rotatable manner with respect to thevibration element and that the second transmission unit has at least asecond pivot bearing, via which the inner drive shaft is supported in arotatable manner with respect to the vibration element. The transmissionunits designed as pivot bearings enable the vibration element to beprovided in a non-rotating manner in a housing of the drive device. Forthe transmission of the vibration the pivot bearings are preferablydesigned as axial bearings that ensure the transmission of axial forces.

According to the invention it is preferred that via an engaging element,in particular an engaging tooth system, the outer drive shaft and/or theinner drive shaft is supported in an axially displaceable manner on adrive element that drives the drive shaft in a rotating manner. Theouter drive shaft and/or the inner drive shaft has an external toothsystem, for example, that is in engagement with a tooth system of thedrive element. The drive element can be designed, in particular, as ahollow shaft with internal tooth system. By way of the engaging toothsystem the outer drive shaft and/or the inner drive shaft is supportedin an axially displaceable manner with respect to the drive element.Consequently, the engaging tooth system ensures on the one hand thetransmission of a torque to the drive shaft and on the other hand adecoupling of the drive shaft in the axial direction with respect to thedrive element so that the vibration of the drive shaft is nottransmitted to the drive element or the rotary drive unit.

An especially compact and stable drive device is achieved in that atleast one of the rotary drive units and the vibration unit are arrangedon a common receiving part or support and in that the vibration unit issupported in an axially movable manner on the common receiving part orsupport. The rotary drive unit preferably comprises a frame or housingwhich is firmly connected to the receiving part. Between the vibrationunit, more particularly the vibration element, and the receiving parte.g. an elastic element, as for example a rubber bearing, can bearranged. As a result of the decoupling of the vibration unit from thereceiving part, a transmission of the vibration via the receiving partto the rotary drive unit is largely avoided.

An advantageous coupling of the vibration unit with both drive shaftscan be attained in that the vibration unit is arranged between the firstrotary drive unit and the second rotary drive unit.

Furthermore, it is preferred that the first transmission unit isarranged on a first axial side of the vibration element and the secondtransmission unit is arranged on a second axial side of the vibrationelement. In this way, an even loading of the vibration unit and a goodtransmission of the vibration to the drive shafts is achieved.

By preference, the inner drive shaft is passed through the vibrationelement. This permits the arrangement of the second transmission unitand/or the second rotary drive unit on a side of the vibration unitfacing away from the drill rod.

To transmit the axial forces to the inner and/or outer drive shaft it ispreferred that the vibration element comprises a bearing seat, ofcylindrical shape for instance, on the outer circumference of which thefirst transmission unit and/or the second transmission unit is arranged.Accordingly, the inner drive shaft and respectively the outer driveshaft preferably have a bearing seat, on the inner circumference ofwhich the corresponding transmission unit is arranged.

To adjust an axial relative position between inner rod and outer rodand/or to change a vibration characteristic it is preferred that anactuator is provided, with which the outer drive shaft is axiallyadjustable with respect to the inner drive shaft. The actuator ispreferably arranged between one of the transmission units and thevibration body. With the actuator the position of the transmission unitcan be adjusted with respect to the vibration body. In this way, therespective drive shaft is moved or adjusted axially with respect to thevibration body.

A precise and efficient setting of the relative position between outerand inner drive shaft can be achieved in that the actuator has apositioning cylinder and/or a toothed rack. In particular, thepositioning cylinder can be actuated hydraulically and/or electrically.It is also possible that several actuators are distributed in thecircumferential direction around the drive shaft.

A compact drive device can be provided in that the first transmissionunit and/or the second transmission unit is designed to transmit boththe vibration and a torque. In particular, it is preferred that thevibration of the vibration element can be transmitted via the firstrotary drive unit and/or the second rotary drive unit to the outer orinner drive shaft. For instance provision can be made for the vibrationof the vibration element to be transmitted via a common receiving partto the rotary drive unit and from there via a rotary drive elementserving as a transmission unit to the relevant drive shaft. As atransmission unit the drive element therefore transmits both the torqueand the vibration to the drive shaft.

In the following the invention will be described further by way of theaccompanying schematic drawings, wherein shows:

FIG. 1 a first embodiment of a drive device according to the invention;and

FIG. 2 a second embodiment of a drive device according to the invention.

Identical components or those corresponding to each other are designatedin all Figures with the same reference signs.

FIG. 1 shows a drive device 10 for driving a drill rod not illustratedhere, which comprises an outer rod and an inner rod received therein.

The drive device 10 has a first rotary drive unit 20 for the outer rodand a second rotary drive unit 30 for the inner rod. The first rotarydrive unit 20 comprises an outer drive shaft 22 which can be coupled ina rotationally fixed manner with the outer rod. For this purpose acoupling means is provided in a generally known manner. The outer driveshaft 22 is driven via a drive element 24 by a drive motor 28. The driveelement 24 is designed as a hollow shaft with internal tooth system 25.The outer drive shaft 22 is received in the hollow shaft and comprisesan engaging tooth system 23 designed as an external tooth system whichmeshes with the internal tooth system 25 of the drive element 24 so thata torque can be transmitted to the outer drive shaft 22. The engagingtooth system 23 ensures an axial displacement of the outer drive shaft22 with respect to the drive element 24.

By means of one or several pivot bearings 29 the drive element 24 issupported in a housing 21 of the first rotary drive unit 20. Between thedrive motor 28 and the drive element 24 a drive pinion 26 is arrangedwhich meshes with an external tooth system of the drive element 24.

Correspondingly, by means of the second rotary drive unit 30 an innerdrive shaft 32 is driven in a rotating manner, which can be coupled in arotationally fixed manner with the inner rod. Via a drive pinion 36 adrive motor 38 drives a drive element 34 designed as a hollow shaft. Thedrive element 34 is supported by means of one or several pivot bearings39 in a housing 31 of the second rotary drive unit 30 and comprises atooth system 35, via which a torque can be transmitted to the innerdrive shaft 32. The inner drive shaft 32 has an engaging tooth system 33which is in engagement with the tooth system 35. The engaging toothsystem 33 and the tooth system 35 enable an axial displacement of theinner drive shaft 32 with respect to the drive element 34.

In the axial direction between the first rotary drive unit 20 and thesecond rotary drive unit 30 a vibration unit 40 is arranged. Thevibration unit 40 comprises at least two rotational masses 41 drivablein opposite directions which set a vibration element 42 into a movementoscillating axially to the drilling or longitudinal axis 12. Therotational masses 41 each have a shaft 43 with an eccentric weight 44.The shafts 43 with the eccentric weights 44 are brought into asynchronized rotational movement so that proportions of unbalanced massacting radially to the longitudinal axis 12 are mutually compensated andan axially directed up and down movement of the vibration element 42 isgenerated.

To transmit the vibration generated by the vibration unit 40 to theouter drive shaft 22 a pivot bearing 52 is arranged as a firsttransmission unit 50 between the vibration unit 40 and the outer driveshaft 22. The inner drive shaft 32 is connected to the vibration element42 via a second transmission unit 60 which is designed as a pivotbearing 62. The pivot bearings 52, 62 are designed for the transmissionof axial forces. Hence, the vibration unit 40 is connected to both driveshafts 22, 32 in an axially fixed manner so that both drive shafts 22,32 are simultaneously set into oscillation by the vibration element 42.

The first pivot bearing 52 is located on a first axial side of thevibration element 42 facing towards to the drill rod while the secondpivot bearing 62 is located on a second axial side of the vibrationelement 42 facing away from the drill rod. The outer drive shaft 22 hasa bearing flange 54 at the end with a bearing seat 56 which is formed bya cylindrical inner lateral surface. The inner drive shaft 32 is passedthrough a cylindrical passage opening of the vibration element 42 andcomprises between its engaging tooth system 33 and the vibration element42 a bearing flange 64 with a bearing seat 66 for the pivot bearing 62.

The pivot bearings 52, 62 are arranged in the longitudinal direction ofthe drive shafts 22, 32 between the engaging tooth systems 23, 33 andare each mounted on a bearing seat 46 of the vibration element 42. Thebearing seat 46 is formed by a cylindrical outer lateral surface.

The rotary drive units 20, 30 as well as the vibration unit 40 areconnected to each other via a common receiving part 70 that can also bereferred to as a frame, support or housing. The vibration unit 40 issupported via an elastic element 72 on the receiving part 70.

FIG. 2 shows an alternative embodiment of a drive device 10. In contrastto the embodiment according to FIG. 1 the outer drive shaft 22 and theinner drive shaft 32 are axially adjustable with respect to each other.To this end an adjusting unit with an actuator 48 is provided betweenthe inner drive shaft 32 and the vibration element 42. The bearing seat46 for the transmission unit 60 is arranged in this case on a bearingring 47 movable with respect to the vibration element 42. By means ofthe actuator 48 the bearing ring 47 or the transmission unit 60 can beadjusted axially relative to the vibration element 42 driven in avibrating manner. In this way, the inner drive shaft 32 can be moved inthe axial direction with respect to the vibration element 42. Theactuator 48, which is designed by way of example as a positioningcylinder, can set a predetermined distance of the second transmissionunit 60 with respect to the vibration element 42. Similarly, it would bepossible to adjust the outer drive shaft 22 on the vibration element 42via an actuator 48.

In the embodiments of the drive device 10 illustrated in FIGS. 1 and 2the up and down movement of the vibration element 42 is transmittedindependently of both rotary drive units 20, 30 to the outer drive shaft22 and the inner drive shaft 32. However, in a further embodiment of theinvention provision can also be made for the entire drive device 10 tooscillate jointly with the rotary drive units 20, 30 and the vibrationunit 40 and for the vibrating movement to be transmitted via the rotarydrive units 20, 30 to the outer drive shaft 22 and the inner drive shaft32 respectively. This can be achieved, in particular, in that the driveelements 24, 34 transmit not only a torque to the outer drive shaft 22or the inner drive shaft 32 but also the vibrating movement.

1. Drive device for driving a drill rod, which has an outer rod and aninner rod, with a first rotary drive unit, with which the outer rod canbe driven in a rotating manner via an outer drive shaft, a second rotarydrive unit, with which the inner rod can be driven in a rotating mannerindependently of the outer rod via an inner drive shaft, and a vibrationunit for generating a vibration, which has a vibration element that canbe driven in a vibrating manner, wherein for transmission of thevibration to the outer drive shaft the vibration element is connectedvia a first transmission unit to the outer drive shaft and fortransmission of the vibration to the inner drive shaft the vibrationelement is connected via a second transmission unit to the inner driveshaft.
 2. Drive device according to claim 1, wherein the firsttransmission unit has at least a first pivot bearing, via which theouter drive shaft is supported in a rotatable manner with respect to thevibration element, and the second transmission unit has at least asecond pivot bearing, via which the inner drive shaft is supported in arotatable manner with respect to the vibration element.
 3. Drive deviceaccording to claim 1, wherein via an engaging tooth system the outerdrive shaft and/or the inner drive shaft is supported in an axiallydisplaceable manner on a drive element.
 4. Drive device according toclaim 1, wherein at least one of the rotary drive units and thevibration unit are arranged on a common receiving part and the vibrationunit is supported in an axially movable manner on the common receivingpart.
 5. Drive device according to claim 1, wherein the vibration unitis arranged between the first rotary drive unit and the second rotarydrive unit.
 6. Drive device according to claim 1, wherein the firsttransmission unit is arranged on a first axial side of the vibrationelement and the second transmission unit is arranged on a second axialside of the vibration element.
 7. Drive device according to claim 1,wherein the inner drive shaft is passed through the vibration element.8. Drive device according to claim 1, wherein the vibration elementcomprises a bearing seat, on the outer circumference of which the firsttransmission unit and/or the second transmission unit is arranged. 9.Drive device according to claim 1, wherein an actuator is provided, withwhich the outer drive shaft is axially adjustable with respect to theinner drive shaft.
 10. Drive device according to claim 9, wherein theactuator has a positioning cylinder and/or a toothed rack.
 11. Drivedevice according to claim 1, wherein the first transmission unit and/orthe second transmission unit is designed to transmit both the vibrationand a torque.
 12. Method for driving a drill rod, which has an outer rodand an inner rod, in particular by means of a drive device according toclaim 1, in which by means of a first rotary drive unit the outer rod isdriven in a rotating manner via an outer drive shaft, by means of asecond rotary drive unit the inner rod is driven in a rotating mannerindependently of the outer rod via an inner drive shaft, and by means ofa vibration unit a vibration is generated, wherein the vibrationgenerated by the vibration unit is transmitted via a first transmissionunit to the outer drive shaft and via a second transmission unit to theinner drive shaft.